This invention relates generally to vapor liquid contacting vessel internals and, more particularly, to liquid collectors. The invention will find use in any such vessel and is particularly useful in connection with a distillation column such as a cryogenic distillation column.
Liquid collectors, also known as chimney trays, are trays set below packed beds in a vapor liquid contacting vessel, such as a distillation column, which are used to gather the liquid that falls out of the bottom of the packing. This is done for two reasons. The first is to gather the liquid together so that it can be evenly distributed to the next lower packed bed. All or a portion of it can be withdrawn, or additional liquid can be added at this point. The second reason is to mix the gathered liquid together to even out any concentration gradients imposed by maldistribution in the bed above. The existing method of installing seal welded liquid collectors in vessels is the most time consuming and therefore most expensive part of the installation. The main reason for this is the time involved in seal welding all of the panels together. This welding of two thin sheets of metal is also difficult to perform properly. When it is done incorrectly gaps open at the collector perimeter allowing liquid to leak.
A leak free liquid collector which does not require seal welding of the parts would be highly desirable.
Accordingly it is an object of this invention to provide an improved liquid collector for use in a rectification column. The collector should be easily assembled using any practical and convenient method of attaching the parts.
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention which is:
A collector for use in a vapor liquid contacting vessel comprising:
(A) a central sump having side walls defining a sump volume and having an axial length traversing the collector;
(B) a plurality of spaced deck plates oriented perpendicular to the sump, each deck plate attached to a central sump side wall by fastener means which are positioned over the sump volume; and
(C) a plurality of riser hats, each riser hat positioned between spaced deck plates and overlapping a deck plate, and each riser hat fastened to a deck plate by fastener means positioned over such deck plate.
As used herein the term xe2x80x9cdeck platexe2x80x9d means a long narrow metal plate that is trough shaped in cross section and is closed at the outside end and open at the inside end in order to collect falling liquid and direct its flow into the center sump. The deck plates do the majority of the liquid collection.
As used herein the term xe2x80x9criser hatxe2x80x9d means a long narrow metal plate positioned over the openings between deck plates to prevent falling liquid from leaking through the opening. Similar to the deck plate it is trough shaped, closed on the outside end and open on the inside end in order to direct its liquid into the center sump.
As used herein the term xe2x80x9cboltxe2x80x9d means a fastener means comprising a threaded pin or rod with a head at one end designed to be inserted through holes in assembled parts and secured by a mated nut that is tightened by applying torque. Other fastener means which may be used in the practice of this invention include rivets, screws, spot welds, tack welds, cotter pins, and adhesives.
As used herein the term xe2x80x9ccolumnxe2x80x9d means a distillation or fractionation column or zone, i.e. a contacting column or zone wherein liquid and vapor phases are countercurrently contacted to effect separation of a fluid mixture, as for example, by contacting the vapor and liquid phases on a series of vertically spaced trays or plates mounted within the column and/or on packing elements which may be structured packing and/or random packing elements. For a further discussion of distillation columns, see the Chemical Engineers"" Handbook fifth edition, edited by R. H. Perry and C. H.
Chilton, McGraw-Hill Book Company, New York, Section 13,
Vapor and liquid contacting separation processes depend on the difference in vapor pressures of the components. The high vapor pressure (or more volatile or low boiling) component will tend to concentrate in the vapor phase whereas the low vapor pressure (or less volatile or high boiling) component will tend to concentrate in the liquid phase. Partial condensation is the separation process whereby cooling of a vapor mixture can be used to concentrate the more volatile component(s) in the vapor phase and thereby the less volatile component(s) in the liquid phase. Rectification, or continuous distillation, is the separation process that combines successive partial vaporizations and condensations as obtained by a countercurrent treatment of the vapor and liquid phases. The countercurrent contacting of the vapor and liquid phases is adiabatic and can include integral or differential contact between the phases. Separation process arrangements that utilize the principles of rectification to separate mixtures are often interchangeably termed rectification columns, distillation columns, or fractionation columns. Cryogenic rectification is a rectification process carried out, at least in part, at temperatures at or below 150 degrees Kelvin (K.).